iphone - 将 NSMutableArray 从模态视图 Controller 传递到父 View

Question

我正在努力将 NSMutable 数组从模态视图 Controller 传递回我来自的 View Controller 。

这是我目前的方法:

FirstViewController.h
#import "SecondViewController.h"

@property (strong, nonatomic) IBOutlet NSMutableArray *passedRecipientsArray;


FirstViewController.m
@synthesize passedRecipientsArray = _passedRecipientsArray;

- (void)viewDidAppear:(BOOL)animated {
    NSLog(@"passedRecipientsArray: %@", self.passedRecipientsArray);
}

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    if([[segue identifier] isEqualToString:@"addContact"]){
        UINavigationController *nav = [segue destinationViewController];
        SecondViewController *secondViewController = (SecondViewController *)nav.topViewController;
        secondViewController.emailContact = @"TRUE";
    }
}

---

SecondViewController.h
@property (strong, nonatomic) IBOutlet NSMutableArray *selectedContactsArray;


SecondViewController.m
@synthesize passedRecipientsArray = _passedRecipientsArray;

- (void)closeWindow
{
    if([self.selectedContactsArray count] != 0){
        NSLog(@"PASS ME: %@", self.selectedContactsArray);

        FirstViewController *firstViewController = [[FirstViewController alloc] init];

        if(firstViewController.passedRecipientsArray == nil) firstViewController.passedRecipientsArray = [[NSMutableArray alloc] init];
        firstViewController.passedRecipientsArray = self.selectedContactsArray;

        [self dismissModalViewControllerAnimated:YES];
    }
}

有更好的方法吗？我试过用这个:How to pass object on modal view's dismissal但会很困惑。

有没有人有一个很好的教程/清晰简单的方法来做我想要做的事情？谁能告诉我哪里出错了？

Answer 1

不要在 SecondViewController 内部分配 FirstViewController。因为 FirstViewController 是您的父类。旧的 FirstViewController 对象在重新分配后将null

传递FirstViewController实例而不是写

FirstViewController *firstViewController = [[FirstViewController alloc] init];

示例:

SecondViewController.h

#import "FirstViewController.h"

FirstViewController *firstViewController;

@property (strong, nonatomic) IBOutlet NSMutableArray *selectedContactsArray;
@property (strong, nonatomic)  FirstViewController *firstViewController;

SecondViewController.m
@synthesize passedRecipientsArray = _passedRecipientsArray;
@synthesize firstViewController;

- (void)closeWindow
{
    if([self.selectedContactsArray count] != 0){          

                if(self.firstViewController.passedRecipientsArray == nil)
                       self.firstViewController.passedRecipientsArray = self.selectedContactsArray;         

        [self dismissModalViewControllerAnimated:YES];
    }
}

然后将您的 FirstViewController 修改为

SecondViewController *secondViewController;

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    if([[segue identifier] isEqualToString:@"addContact"]){
        UINavigationController *nav = [segue destinationViewController];
        secondViewController = (SecondViewController *)nav.topViewController;
        secondViewController.emailContact = @"TRUE";
       secondViewController.firstViewController = self;
    }
}